Conflating Disability, Frailty, and Multimorbidity in Adult Spinal Deformity Patients

Retrospective cohort study. To examine the degree of overlap between disability, multimorbidity, and frailty in a cohort of ASD patients. Frailty is a popular topic in spine research, as it is a reported risk factor for poor outcomes. Disability, multimorbidity, and frailty can coexist, sometimes causing or exacerbating one another. It is important to distinguish these conditions for perioperative optimization and to guide research initiatives. A multicenter registry of ASD patients was queried for baseline data regarding frailty, as measured by the Edmonton Frail Scale, disability, as measured by the Oswestry Disability Index, and multimorbidity, as measured by the Charlson Comorbidity Index. The relationships between these measures and both chronological and biological age (PhenoAge) were explored. Exploratory factor analysis (EFA) examined areas of overlap between these diagnoses. There were 861 patients contributing data, mostly female (68%), most undergoing primary surgery at a median age of 66 years (Interquartile Range (55.1-71.6), with 6% classified as "Frail." Chronological and PhenoAge showed weak to moderate associations with disability and frailty, though PhenoAge was stronger. There was no evidence of distinct clusters, rather a continuity of condition severity. EFA found overlap between subjective and objective measures of disability, function, and frailty. Frailty was rare (6%) in this multicenter cohort of patients. Conflation of disability and frailty is a real risk due to overlap in measures of both conditions. Disability and frailty do not form discrete categories but rather exist along a continuum, underscoring the need to abandon categorical labels in favor of continuous measures for both clinical assessment and research settings.